Comby Two-Sided Overlain Gasket for Sealing of Dismountable Flanged Joints

ABSTRACT

Comby two-sided overlain gasket ( 5, 13 ) for sealing of dismountable flanged joints, which comprises two sealing contact surfaces, in which there are created concentric grooves ( 8 ) in a shape of letter V with opening angle of 90°, while on both sealing contact surfaces of the comby gasket ( 5, 13 ) there are between the grooves ( 8 ) created concentric surfaces (Y) of a constant width from 0.2 mm to 0.6 mm, while the bottoms of the concentric grooves ( 8 ) are created by rounding (R) having radius of 0.3 mm to 0.5 mm.

TECHNICAL FIELD

The invention relates to the comby two-sided overlain gasket for sealing of dismountable flanged joints, for example of flanged joints on pipings, fittings, pressure vessels, etc., while the profile of the comby gasket is formed of grooves of a shape of letter V with opening angle of 90°.

BACKGROUND ART

The known comby gaskets for dismountably arranged flanged joints, fittings, pressure vessels, etc., are as a rule of a ring shape, or of annulus shape, whose cross-section is of various shape, this usually depending on material, that is used for sealing of the flanged joint. As a rule, the flanges are mutually connected by means of screws, through which a dismountable connection is obtained. The dismountable connection is advantageous for executing repairs, reconstructions, etc.

There are known comby gaskets, which are made of soft alloy steel or austenitic steel. Mostly the comby gasket is overlain on both sides with sealing board or foil from expanded graphite, expanded teflon, thermiculite, mica, aluminum, nickel, silver, etc. Selection of a particular material used for the sealing plate or sealing foil is affected especially by chemical-physical properties of the media, which is led by the pipeline system or which is present in the sealed pressure vessel.

Gaskets for flanged joints are usually of a ring shape and are on the contact sealing surfaces provided with concentric grooves having a shape of letter V with opening angle of 90°, spacing of 1.5 mm and depth of 0.75 mm. The mentioned grooves having a shape of letter V cause, in conjunction with sealing lining, a transformation of the sealing lining when being compressed between the sealing compression surfaces of flanges. Through this transformation of the sealing lining the sealing effect of the flanged joint is increased. Achievement of the most efficient sealing effect with the longest operational reliability of the sealed flanged joint is influenced not only by the chemical properties of the medium led in the pipeline, but also by its temperature and pressure. Demandingness to the mentioned sealing effect is further increased in a case when the pressure or temperature, eventually both these physical values, are varying during operation of the pipeline in a relatively large range. The mentioned sealing effect of a flanged joint is also influenced by a specific pressure caused by the screws, which mutually join and tighten the flanges, are provided on the pipeline or on pressure vessels, and which are dimensioned from structural and shape point of view in a proper manner.

There is known a comby gasket on both sides overlain with a foil of expanded graphite, that features very good sealing properties even at high specific pressures and high temperatures. Upon compressing of the comby gasket between the sealing surfaces of flanges, the foil from expanded graphite is being subject to transformation into its grooves. During installation it is necessary to secure the compressing so that between the peaks of grooves created on the contact surface of the comby gasket and the sealing compression surface of the flange a continuous layer of expanded graphite is present. If, due to installation works or during working stress of the flanged joint, a direct contact of groove peaks in contact surfaces of comby gasket with sealing compression surface of the flange occurs, then the foil of expanded graphite is cut through and the sealing principle of auxiliary sealing stream, which was created by enclosing the expanded graphite in the grooves of the comby gasket, is disturbed. Through this the sealing effect of flanged joint is devalued and it is necessary to execute a repair. Moreover, in such case there are quite often galls on sealing surfaces of flanges, which increases requirements for executing the repair.

The above mentioned shortcoming, which is caused by mating respectively by a direct contact of the comby gasket with sealing surfaces of flanges, is considerably restricted by the fact that the comby gasket provided with grooves of a shape of letter V and opening angle of 90° is between the individual grooves provided with bridges having width of 0.25 mm to 0.4 mm. Fitting this foil to the comby gasket facilitates sticking of sealing foil to the comby gasket, as well as improvement of conditions for executing of installation and maintenance works. It is advantageous to use an adhesive, whose adhesion could be affected already by lower temperatures.

The flanged joints are in some cases applied in pipeline systems, that feature a considerable, nearly extraordinary mechanical as well as heat stress. In these cases, especially at flanged joints of larger diameters, this stress worsens the sealing effect, service life and reliability of sealing joint, the level of achievable surface parallelism of contact surfaces of flanges being connected. Non-parallelism of contact connection surfaces of flanges as well as their possible surface deformations and irregularities, make the installation works more demanding and negatively influence parameters of sealing effect, especially in a case when an annular comby two-sided overlain gasket is used for sealing of the joint.

The goal of the submitted technical solution according to the invention is to achieve improvement of background art and to optimise conditions for production of the most operationally reliable sealing effect by the flanged joints, as well as reduction of negative impact of non-parallelism and deformations of surfaces of flanges being connected, this also at utilisation of know-how for installation and servicing works.

PRINCIPLE OF THE INVENTION

The goal of the invention has been achieved through a comby two-sided overlain gasket for sealing of dismountable flanged joints, whose principle consists in that, on both sealing contact surfaces of comby gasket there are between the grooves created concentric surfaces of a constant width from 0.2 mm to 0.6 mm, while the bottoms of the concentric grooves are created by rounding having radius of 0.3 mm to 0.5 mm.

At the same time it is preferred, if the sealing contact surfaces and contact surfaces of flanges are worked to a grade of 1.6 to 3.2 of standardised hardness.

Further improvement of sealing effect, especially of comby gaskets for cover of a pressure vessel may be achieved, when each sealing contact surface of the comby gasket comprises at least two groups of grooves of a different depth and the individual groups of grooves are mutually separated by a continuous recess of a shape of annulus.

For an easier installation and disassembly it is preferred if sealing foils or sealing plates are stuck on both sealing contact surfaces of comby gasket using an adhesive of relatively low melting point, e.g. cca 50° C.

Further advantage of the solution according to the invention consists in that the concentric grooves in sealing contact surface of the comby gasket are of a less volume than the volume of sealing foil or sealing plate, by which the respective sealing contact surfaces are overlain.

To achieve a long-term reliable sealing effect and to decrease the negative impact of non-parallelism and deformation of surfaces of flanges being connected it is preferred if each of the sealing contact surfaces of the comby gasket is created on an independent annular part, which are on an inner diameter bent in the direction to one another and in a contact place are connected, while on the outer side they mutually overlap, and at least in one of them there is created an annular recess, which forms upon connection of both annular parts the annular chamber. Connection of both annular parts is formed either by a fixed edge joint, e.g. by a weld or by a dismountable joint, e.g. by a locking offset.

From the point of view of economy for reliable achievement of sealing effect it is preferred, if the annular chamber is of a square or rectangular cross-section.

Further it is preferred if at least one of the annular parts is upon acting of axial compression force springy flexible.

Preferably, in the annular chamber an annular springy insertion of expanded graphite is mounted, which further decreases effect of non-parallelism and deformations of connected surfaces of flanges during operation.

DESCRIPTION OF THE DRAWING

Exemplary embodiment of invention is represented in the drawings, where:

The FIG. 1 shows partial axial cross-section through flanges connecting the pipeline with the comby gasket, which is two-sided overlain by a sealing foil, what everything is of an annular shape,

the FIG. 2 partial cross-section through a flange forming the end of a pressure vessel which is sealed by a cover by means of two-sided overlain comby gasket, at which two groups of grooves of a different depth are applied,

the FIG. 3 in partial cross-section and in an enlarged scale a profile of a shape of grooves formed on the comby gasket,

the FIG. 4 shows in an enlarged scale a partial cross-section through the flange, comby gasket and the sealing foil after its compressing in a flanged joint,

the FIG. 5 partial axial cross section through the flanges connecting the pipeline with the comby longitudinally split gasket provided with a springy insertion, while the comby gasket is two-sided overlain with sealing foil and everything is of an annular shape,

the FIG. 6 cross section through the comby longitudinally split gasket with marked difference of compressibility between the surfaces of annular parts of a gasket as a result of action of axial compression of flanges being connected,

the FIG. 7 partial axial cross section through flanges connecting the pipeline with the comby longitudinally split gasket as in the FIG. 5, nevertheless with the difference, that there is shown the setting of sealing elements after compressing by means of contact surfaces of flanges being connected,

the FIG. 8 partial cross-section, in an enlarged scale the detail “A” in the FIG. 5, representing connection of annular flat parts on their inner diameter by means of a locking offset, and

the FIG. 9 shows partial cross section as in the FIG. 8 with the difference, that there is shown connection on an inner diameter by means of a weld.

EXAMPLES OF EMBODIMENT

The upper flange 1 (FIG. 1) at the end of not represented pipeline is provided with holes 2 designed for the not represented connection screws. Also the lower flange 3 at the end of connected not represented pipeline is provided with holes 4 for the mentioned connection screws. Method and embodiment of this flanged joint is commonly known. Into the space between contact surfaces of flanges 1, 3 the comby annular gasket 5 is inserted. The comby gasket 5 is on two sides overlain with sealing foil or sealing plate 6, 7 also of an annular shape, whose outer as well as inner diameter is preferably identical with an inner and outer diameter of annular comby gasket 5. The sealing contact surfaces of annular comby gasket 5 are provided with concentric grooves 8, between which on both sealing contact surfaces there are created concentric surfaces Y. Width of surface Y is usually selected in the range from 0.2 mm to 0.6 mm and it depends not only on the material used for production of the sealing foil or sealing plate 6, 7, but also on the pressure, temperature and medium, that is led through the pipeline connected by means of the mentioned flanged joint. In bottom section of the grooves 8 the rounding R having diameter of 0.3 to 0.5 mm is created. The created rounding R positively influences distribution of tension caused by the foil or plate 6, 7 towards the bottom of the grooves 8 upon tightening of flanged joint by a compression effect. This structural provision positively influences reliability as well as total service life of sealing of the flanged joint.

A not represented pressure vessel is ended up by flange 9 (FIG. 2) and is on its perimeter provided with holes 10 for the not represented connection screws. Closing of the pressure vessel is created by a cover formed of covering flange 11, also on its perimeter provided with holes 12 for connection screws. Also this method of closing the pressure vessels is commonly known.

Between the flange 9 of pressure vessel and the cover formed of covering flange 11 there is inserted the annular comby gasket 13, which is in the represented embodiment on its contact sealing surfaces provided with two systems of concentric annular grooves 14, 15 of a different depth S. The system of deeper concentric grooves 14 is from the system of shallower concentric grooves 15 separated by an annular recess 16. Also this embodiment of the annular comby gasket 13 is on both sides overlain with the sealing foil or sealing plate 17, 18. Application of different depth of annular grooves 14, 15 is an advantageous technical provision that enhances the sealing effect, especially in case of surface deformation of the cover formed of the covering flange 11, which may occur due to pressure in the pressure vessel.

After the screws of the flanged joint are tightened, the sealing foil or the sealing plate 6, 7 is also with the comby gasket 5 compressed so that in the space between contact surfaces of the flanges 1, 3, 9, 11, and surfaces Y between the grooves 8 of comby gasket 5 there is to be found a compact integral layer X of a material of the sealing foil, possibly of sealing plate 6, 7, respectively 17, 18. Thickness of this compact integral layer X is in practice determined to be in the range of 0.02 mm to 0.3 mm, this depending on material used for the sealing foil or sealing plate 6, 7 respectively 17, 18, as well as on pressure and temperature of medium being sealed by the flanged joint. Thickness of the compact integral layer X (FIG. 4) of material of the sealing foil or of sealing plate 6, 7, 17, 18 after tightening of the flanged joint has an immediate impact on the achieved sealing effect. Inadequately great thickness of the layer X of material causes especially due to acting of pressure that the material of sealing foil or of sealing plate 6, 7, 17, 18 is pushed away, thus causing the undesirable reduction of sealing effect in the flanged joint.

The shape and dimensional arrangement of the comby two-sided overlain gasket for sealing of dismountable flanged joints has a volume of inner space of the grooves 8 of comby gasket 5, 13 smaller than the volume of sealing foil or of sealing plate 6, 7, 17, 18 after tightening of flanged joint.

To facilitate installation works, including maintenance works, it is advantageous if the comby gasket 5, 13, is on both sides overlain with sealing foil or sealing plate 6, 7, 17, 18, stuck by adhesive of relatively low melting point, e.g. of cca 50° C. The mentioned advantage consists in that by acting of heat there are created conditions for easier and troublefree removal of damaged sealing foil or plate 6, 7, respectively 17, 18.

The described technical solution according to the invention is applicable for pipelines and pressurised systems, in which the sealed medium has a high transportation pressure, e.g. pressure of 100-150 MPa, and varying temperature that may reach more than 500° C. Solution according to the invention may also be applied for the systems working with underpressure.

Material, which is used for the sealing foil or sealing plate 6, 7, 17, 18 is as a rule subjected to parameters and properties of the sealed medium, which means that adequately suitable material except for expanded graphite is also e.g. expanded teflon, silver, thermiculite, aluminum, special fibrous-rubber materials, etc.

In example of embodiment according to the FIGS. 5 and 7 the flange 1 at the end of not represented pipeline is provided with holes 2 designed for the not represented connection screws. Also the lower flange 3 at the end of joined not represented pipeline is provided with holes 4 for the mentioned not represented connection screws. Into the space between the contact surfaces of flanges 1, 3 there is inserted the annular comby gasket 5. The comby gasket 5 is from both sides overlain by a sealing foil or sealing plate 6, 7 also of annular shape, whose outer as well as inner diameter is preferably relatively identical with inner and outer diameter of the annular comby gasket 5. The annular comby gasket 5 is made of two annular flat parts 5 a, 5 b and their inner diameter is ended by bending 51. Annular flat parts 5 a, 5 b are preferably in its surface shaped as a mirror-image with the exception of their ending on outer circumference. One of the annular flat parts, e.g. the part 5 a, on the outer circumference is provided with vertical detent 52, which displaceably overlaps the outer circumference of the second oppositely arranged part 5 b. Outer surface of annular flat part 5 a is provided with concentric grooves 8 a, and the outer surface of opposite annular flat part 5 b is provided with concentric grooves 8 b. At least one of the annular flat parts, e.g. 5 a is on the inner surface provided with a recess, which after assembly of both annular flat parts 5 a, 5 b forms a lockable chamber 53 of rectangular or square shape. The lockable chamber 53 is due to its bending 51 and a fixed connection by the weld 55 a, or by locking offset 55 b, on inner diameter of the mentioned annular flat sections 5 a, 5 b ended in the direction to the inner diameter by a space 54 of triangular shape.

Upon assembly of the annular comby gasket 5 it is suitable from the point of view of technology, before creating the fixed, especially non-dismountable, joint of annular flat parts 5 a, 5 b, on their inner diameter, that into the space of lockable chamber 53 is inserted an annular springy insertion 20 of expanded graphite or other material with anti-extrusive properties, that secure stability of the preload being set, including the ability of back recovery. Thickness of the springy insertion 20, of rectangular or square diameter, is structurally dimensioned depending on diameter of flanged joint being sealed, on operational pressure and temperature of medium led by pipeline, optimum axial compressing of flanges being connected in direction of arrows P₁ and P₂ and also taking into account usability of adjustable preload shown graphically by the illustrated value W.

The surface flexibility, respectively ability of surface flexibility of annular flat parts 5 a, 5 b in cooperation with property of flexible elasticity of the material, from which the springy insertion 20 is produced, enables that in cases of adequate deformation or adequate non-parallelism of contact surfaces of connected flanges 1, 3 in cooperation with know-how respected during assembly of flanged joints, and at simultaneous utilisation of principle of the technical solution according to the invention, a relatively perfect sealing effect with long-term service life was achieved.

INDUSTRIAL APPLICABILITY

Technical solution according to the invention is applicable for pressurised and underpressurized pipeline systems in which, according to the operational needs, both the pressure as well as temperature of medium being sealed is varying. Testing of such sealed flanged joints verified their reliability as well as their service life at pressures above 150 MPa and temperatures above 500° C.

LIST OF REFERENTIAL MARKINGS

-   1 upper flange -   2 holes -   3 lower flange -   5 comby gasket -   5 a, 5 b annular flat parts of comby gasket -   51 bending -   52 vertical detent -   53 chamber -   54 space of triangular shape -   55 a weld -   55 b locking offset -   6, 7 sealing foil or plate -   8 concentric grooves -   8 a, 8 b concentric grooves -   9 flange -   10 holes -   11 covering flange -   12 holes -   13 comby gasket -   14 deeper concentric grooves -   15 shallower concentric grooves -   16 annular recess -   17, 18 sealing foil or plate -   20 springy insertion -   Y concentric surface -   R radius of groove rounding -   S groove depth -   X layer of material 

1. Comby two-sided overlain gasket (5, 13) for sealing of dismountable flanged joints, which comprises two sealing contact surfaces, in which there are created concentric grooves (8) in a shape of letter V with opening angle of 90°, characterised in that, on both sealing contact surfaces of the comby gasket (5, 13) there are between the grooves (8) created concentric surfaces (Y) of constant width from 0.2 mm to 0.6 mm, while the bottoms of the concentric grooves (8) are created by rounding (R) having radius of 0.3 mm to 0.5 mm. 2-11. (canceled) 